1876.) The Probable Danger from White Ants. 407 
in some cases of ruptures of dams, so frequent of late years, 
white ants may have had some part at least in helping the de- 
struction. The same remark applies to wooden bridges. I can 
only give one fact which I believe belongs here. Near Porter’s 
Station, in Cambridge, was a wooden bridge for cattle driving, 
which gave way, as it was stated, by a large number of cattle 
running across it. Trains stop forty times or more daily at Por- 
ter’s Station, and the bridge was so situated just above the engine 
that it was moistened by the hot steam, the best accommodation 
which white ants would choose. I am told that the broken wood 
had been sound, but I can state that white ants swarmed last 
year on both ends of the broken bridge. Even now the out- 
side of the old bridge remains near the newly-built one, and the 
wood is thoroughly rotten and eaten by insects. I have always 
wondered that houses were never attacked. Now it is done. 
Some years ago, Mr. Alvan Clark, the world-wide known maker 
of astronomical instruments, visited the Museum of Comparative 
Zoölogy. When I showed hir the biological collection of white 
ants, he told me that he knew them very well, because they 
swarmed every year in January in his workshop. Afterwards, 
while I was on a visit there, he showed me that the timber around 
the furnace in his shop was entirely infested by them. This year, 
suddenly the ceiling above the furnace, where the wood is con- 
stantly moistened by hot steam, gave way for about an inch, and 
he was obliged to support the whole by posts and jack-screws. 
A gentleman from Roxbury, when I showed him wood damaged 
by white ants, told me that an old shanty on his estate came 
down, and the wood looked just like the piece I showed him. 
From some lumbermen I heard that such wood was known by 
the name of powder-dust, and I found beautiful pieces of it 
among large piles of lumber near Lake Winnipiseogee. I am 
happy to state that I know of no other damage done here by 
white ants. But their habit of working without injuring the 
Suter surface of the eaten wood, and the immense damage done 
bya nearly-related species, makes it a duty, I believe, for every- 
y to be on his guard. White ants are every year swarming 
around the Museum of Comparative Zoélogy, the Botanical Gar- 
den, and the Observatory. Collections and large libraries are in 
e neighborhood, and it should not be forgotten that A. von 
Humboldt stated half a century ago that the rarity of old books 
i New Spain was the consequence of the depredations of white 
ants. I have no proof that white ants are living in the city of 
